(I)Combined seals

1.Step seal: The Step seal structure is similar to that of the Glyd ring, and is composed of an O-type rubber seal and a special rectangular or trapezoidal seal filled with polytetrafluoroethylene. Step seals can be divided into hole seals and shaft seals, which only have a one-way sealing effect. Step seals are characterized by low friction, no creeping, and long service life. In high-pressure and low-pressure hydraulic systems, Step seals are used as piston rod seals and can be used in reciprocating, vibrating, and spiral motion devices. It is suitable for media such as petroleum-based hydraulic oils and environmentally friendly and safe hydraulic oils, and is widely used in presses, excavators, metallurgical machinery, loaders, chemical machinery, and other occasions.

2.Glyd ring: Glyd ring is composed of an O-type rubber seal and a square seal filled with polytetrafluoroethylene. It can be divided into hole and shaft use. The sealing mechanism is to generate a higher initial contact stress on the sealing surface based on its own deformation to prevent the leakage of pressureless liquid. When the hydraulic cylinder is working, the pressure oil causes the elastic deformation of the O-ring to squeeze the square seal ring, making it close to the sealing surface, and together with the initial contact stress, prevents the leakage of pressure oil. Glyd ring has good O-ring elasticity, low friction coefficient and self-lubricating performance of polytetrafluoroethylene ring, and is widely used in oil cylinder systems.

3.Polypak seal: The polypak seal is composed of a synthetic rubber O-ring and a cloth-reinforced rubber Y-ring. It relies on its own deformation to produce a high initial contact stress on the sealing surface to prevent leakage. When the hydraulic cylinder is working, the pressure oil causes the elastic deformation of the O-ring, always squeezing and stretching the sealing lip of the Y-ring, making it close to the sealing surface, and together with the initial contact stress, prevents the leakage of pressure oil.

(II) Lip seal

1. U-ring: The U-ring has good sealing performance, but it is easy to roll over when used alone, and the friction resistance increases with the increase of pressure. Therefore, the U-ring is only suitable for hydraulic cylinders with low working pressure or low movement speed.

2. V-shaped sealing ring: V-shaped sealing ring must be used with supporting ring and pressure ring, with good sealing performance, and the number of sealing rings can be determined according to the pressure. However, its structure is complex and the friction resistance is large, so it is only suitable for hydraulic cylinders with low movement speed and high working pressure.

3. YX-shaped sealing ring: The aspect ratio of the YX-shaped sealing ring is greater than 2, the working lip is shorter than the non-working lip, and it is divided into hole and shaft. It will not roll when used, and is suitable for high-pressure and high-speed hydraulic cylinders.

(III) O ring

The O ring has an O-shaped cross-section, a simple shape, and is made of rubber. Its wear resistance is not as good as polyurethane. It is mainly used for static sealing of hydraulic systems. O rings are rich in variety and suitable for various materials. The size and grooves are standardized. By selecting suitable rubber materials and appropriate formula design, it can achieve effective sealing for oil, water, air, gas and various chemical media. It has a wide temperature range and is easy to install. It is widely used in sealing of diesel locomotives, automobiles, tractors, construction machinery, machine tools and various hydraulic and pneumatic components.